[Flex Index] : Error when passing invalid value for use_fts param needs to be changed

Build : 7.0.0-1834

When an invalid value is passed to the use_fts param, like in the below listed query, n1fty throws the following error.
"errors": [

{"code":1040,"msg":"Error processing use_fts - cause: unable to parse tristate as a boolean"}

],

curl -u <username:password> -v http://172.23.105.14:8093/query/service -d 'statement=explain select name from `travel-sample` use index(using fts) where city="San Jose"&use_fts=abc'

It would be good if the error msg can be changed.